Valve, especially rotary piston valve, and exhaust gas return system comprising such a valve

ABSTRACT

The invention relates to a valve, especially a rotary piston valve ( 1 ), for controlling the temperature and quantity of the returned exhaust gas in internal combustion engines. Said valve comprises a valve housing ( 2 ) and a control element ( 3 ) disposed therein which interacts with a valve face ( 14 0 configured in the valve housings ( 2 ), the control element ( 3 ) having a conical surface area ( 10 ).

The invention relates to a valve, especially a rotary piston valve,according to the preamble of claim 1 and to an exhaust gas return systemin which at least one corresponding valve is arranged.

DE 103 21 637 A1 discloses a device for regulating the temperature andquantity of the returned exhaust gas in internal combustion engines, inwhich a valve housing of a regulating valve is linked or connected to aheat exchanger or heat exchanger part. The regulating valve is actuatedespecially by means of an electric actuation element, to the input ofwhich can be applied an input signal dependent on the engine parameters.The inflow connection of the valve housing is in gas-transmittingconnection with an inflow gap or an inflow port. The inflow gap isincorporated into or accommodated in the throughflow space, containingthe rotatable/displaceable regulation element, of the valve housing ofthe regulating valve. The first outflow gap of the throughflow space isconnected to the inflow cross section of the exhaust line by means of atransfer space. The second outflow gap of the throughflow space isconnected to an inflow cross section of the heat exchanger by means ofthe distributor space. In the middle position of therotatable/displaceable regulation element, the inflow gap is closed bymeans of a surface, such as a surface of a cylinder. In the firstactivated position, the inflow gap is connected in a gas-transmittingmanner to the first outflow gap in the direction of the exhaust line. Inthe second activated position, the inflow gap is connected in agas-transmitting manner to the second outflow gap in the direction ofthe heat exchanger. The regulation element is formed by a body ofcylindrical basic configuration which is arranged rotatably in acylindrical reception space. The body, in the rotatable embodiment isarranged on a valve stem and has two edges for control, the two edgesbeing formed by three-dimensional curves which run on the surface area.

However, a valve of this type still leaves much to be desired.

The object of the invention is to improve a valve of the type initiallymentioned.

This object is achieved by means of a valve having the features of claim1 and of claim 14. Advantageous refinements are the subject matter ofthe subclaims.

According to the invention, a valve, especially a rotary piston valve,is provided, which serves for regulating the temperature and quantity ofthe returned exhaust gas in internal combustion engines, with a valvehousing and with a regulation element which is arranged in the latterand which cooperates with a valve seat formed in the valve housing, theregulation element having a conical surface area in contrast to thecylindrical surface area, such as is known from DE 103 21 637 A1. Thatsurface of the valve housing which cooperates with the surface area ofthe regulation element, that is to say the valve seat, is preferablyconically designed correspondingly, that is to say with the same vertexangle, so that a gap-free fit and therefore good sealing off areensured.

The vertex angle of the cone is preferably 30° to 90°, especiallypreferably 40° to 50°. The closing action is very good especially in thelast-mentioned vertex angle range.

The regulation element is mounted rotatably in the valve housing, and itcan preferably also be somewhat displaceable in the longitudinaldirection in special angular positions, so that, during actuation,friction is reduced. In this case, the surface areas of the regulationelement and of the valve seat are in bearing contact one against theother preferably only in the completely closed state. In all other(opening) positions, there is a small gap between the surface areas. Inspite of the gap present in most positions, dirt particles are scrapedoff during a rotation of the regulation element, so that a clogging ofthe gap is prevented. In order also to ensure scraping off and at thesame time keep friction as low as possible, the regulation element isdisplaceable in the longitudinal direction by at most 0.5 mm, preferablyby at most 0.1 mm, thus resulting in very low gap heights between thesurface areas.

Preferably, the valve is actuated with the aid of a pressure-regulatedvacuum cell or an electric motor, although any other desired devices foractuation, that is to say for rotating the valve stem, are possible.

The valve stem on which the regulation element is arranged preferablyprojects through a sleeve which is fixed with respect to the valvehousing and which is preferably arranged in a cover connected firmly tothe valve housing. The sleeve in this case serves for mounting the valvestem.

The sleeve fixed with respect to the valve housing preferably has, inone end face, a groove which runs in the radial direction and whichcooperates with a projecting region which is formed on a disk arrangedfixedly in terms of rotation on the valve stem. This allows an automaticmechanical displacement of the valve stem and therefore also theregulation element in the axial direction in the predetermined position.If bearing contact between the surface areas is to be afforded invarious positions, then a plurality of grooves may correspondingly beprovided. The groove may likewise also be designed to be wider than theprojecting region, so that bearing contact between the surface areas isafforded in an angular range, not only in the closing position.

The valve stem preferably has arranged on it at least one spring,especially a cup spring, which by its spring force allows an optimalpositioning of the regulation element, but, in the case of correspondingforces, also allows a longitudinal displacement of the valve stemtogether with the regulation element.

The valve, which has a regulation element arranged rotatably in thevalve seat, is designed, according to the invention, in such a way thatit regulates the throughflow quantity of the fluid supplied to the valvethrough a first port, in a first angular position range, with the secondport closed, in the form of straightforward regulation of thethroughflow to a third port, in a subsequent second angular range in theform of a regulation of the fluid distribution to the second and thethird port, and, in the following third angular range, in the form of astraightforward regulation of the free cross section of the second port,with the third port completely closed. In this case, the regulationelement arranged rotatably in the valve seat preferably has a conicalcontour, with the aid of which it closes or releases the first portcompletely or, preferably continuously, partially.

The relation between the angular position of the regulation element andthe cross section released for the throughflow of the fluid ispreferably essentially linear in the region of the first angular rangeand/or of the third angular range, although slight deviations fromlinearity may occur especially in the initial and/or final region oflinear regulation.

Preferably, an absolute maximum of the released cross section betweenthe first and the second angular range is provided. Especially when thevalve is used for regulating a returned exhaust gas stream, the presenceof a maximum in the case of the complete opening of the outlet to theexhaust gas cooler and the associated slight pressure drop is expedient.

The cross section released overall is preferably essentially constant inthe second angular range.

The invention also relates to an exhaust gas return system with aninternal combustion engine, especially an engine, which is supplied withexhaust gas branched off at an extraction point and returned via areturn point. The object specified above is achieved, in the exhaust gasreturn system, in that a heat exchanger valve device with a valvedescribed above is inserted between the extraction point and the returnpoint.

A preferred exemplary embodiment of the exhaust gas return system ischaracterized in that the heat exchanger valve device is connected to anexhaust gas cooling device. The exhaust gas cooling device serves forlowering the temperature of the returned exhaust gas. The heat exchangervalve device may be tied to the exhaust gas cooling device in amaterially integral way or mechanically.

A further preferred exemplary embodiment of the exhaust gas returnsystem is characterized in that the heat exchanger valve device isintegrated into the exhaust gas cooling device. It is advantageous, forexample, if the housing or the outflow side of the heat exchanger valvedevice forms directly the inlet or outlet diffuser of the exhaust gascooling device respectively.

A further preferred exemplary embodiment of the exhaust gas returnsystem is characterized in that the heat exchanger valve device isconnected in a materially integral manner to the exhaust gas coolingdevice. Alternatively, the heat exchanger valve device may be connectedto the exhaust gas cooling device mechanically.

A further preferred exemplary embodiment of the exhaust gas returnsystem is characterized in that the heat exchanger valve device has abypass. The bypass serves, for example during a cold start of theengine, for conducting the returned exhaust gas, uncooled, past theexhaust gas cooling device.

A further preferred exemplary embodiment of the exhaust gas returnsystem is characterized in that the exhaust gas cooling device comprisesa U-flow cooler. The U-flow cooler is connected to the heat exchangervalve device such that the returned exhaust gas, on the one hand, can beconducted, uncooled, past the cooler by means of the heat exchangervalve device. On the other hand, the returned exhaust gas can beconducted by means of the heat exchanger valve device through the U-flowcooler and thus be returned, cooled. The U-flow cooler affords theadvantage that a bypass may be dispensed with.

A further preferred exemplary embodiment of the exhaust gas returnsystem is characterized in that the heat exchanger valve device isarranged upstream or downstream of the exhaust gas cooling device, asseen in the flow direction from the extraction point to the returnpoint. The heat exchanger valve device may consequently be arranged bothin front of and behind the exhaust gas cooling device.

A further preferred exemplary embodiment of the exhaust gas returnsystem is characterized in that the heat exchanger valve devicecomprises a high-temperature exhaust gas cooler and a low-temperatureexhaust gas cooler. The two-stage cooling may be advantageous, dependingon the application.

A further preferred exemplary embodiment of the exhaust gas returnsystem is characterized in that the heat exchanger valve device isarranged upstream or downstream of the high-temperature exhaust gascooler or of the low-temperature exhaust gas cooler, as seen in the flowdirection from the extraction point to the return point. The heatexchanger valve device may thus be arranged in front of or behind thehigh-temperature exhaust gas cooler or low-temperature exhaust gascooler. However, the heat exchanger valve device may also be arrangedbetween the high-temperature exhaust gas cooler and the low-temperatureexhaust gas cooler.

A further preferred exemplary embodiment of the exhaust gas returnsystem is characterized in that the exhaust gas return system is formedby a high-pressure exhaust gas return system. The high-pressure exhaustgas return system may be equipped with single-stage or with two-stagecooling.

A further preferred exemplary embodiment of the exhaust gas returnsystem is characterized in that the exhaust gas return system is formedby a low-pressure exhaust gas return system. The low-pressure exhaustgas return system may be equipped with single-stage or with two-stagecooling.

The invention is explained in detail below by means of an exemplaryembodiment having various uses in exhaust gas return systems, withreference to the drawing in which:

FIG. 1 shows a perspective view of a valve according to the invention,

FIG. 2 shows another perspective sectional view of the valve of FIG. 1,

FIG. 3A-3C show side views of the rotary piston from different angles,

FIG. 4A shows a diagrammatic illustration to make clear the basicprinciple in the form of an exploded illustration of the rotary pistonand the valve seat, illustrated in simplified form,

FIG. 4B shows the rotary piston and valve seat of FIG. 4A in theassembled state to make clear the function of the control edge,

FIG. 5 shows a regulating curve with an illustration of the valvepositions,

FIG. 6A, 6B show perspective illustrations of the valve housing, theillustration of FIG. 6B being illustrated in section in the longitudinaldirection of the exhaust gas inlet.

FIG. 7 shows a sectional perspective illustration of a detail of thevalve stem and its guidance and sealing off,

FIG. 8 shows a variant of the valve according to the invention in aperspective illustration of a detail of the valve stem and its guide,the disk and the sleeve being additionally illustrated laterally on theleft in another perspective,

FIG. 9 shows a perspective view of the actuation of the valve,

FIG. 10 shows a perspective view of the actuation of the valve accordingto an alternative form of actuation,

FIG. 11 shows a high-pressure exhaust gas return system withsingle-stage cooling which comprises a bypass,

FIG. 12 shows a high-pressure exhaust gas return system withsingle-stage cooling having a U-flow cooler,

FIG. 13 shows a high-pressure exhaust gas return system with two-stagecooling,

FIG. 14 shows a low-pressure exhaust gas return system with single-stagecooling which comprises a bypass,

FIG. 15 shows a low-pressure exhaust gas return system with single-stagecooling having a U-flow cooler, and

FIG. 16 shows a low-pressure exhaust gas return system with two-stagecooling.

A rotary piston valve 1 for regulating the temperature and quantity ofthe returned exhaust gas in internal combustion engines, as is describedwith reference to FIGS. 11 to 16 at a later juncture by means of sixdifferent applications in exhaust gas returns, which consists of a valvehousing 2 and of a regulation element 3 in the form of a speciallydesigned rotary piston, is firmly mounted with its valve housing 2 on aheat exchanger part and, according to the present exemplary embodiment,is welded thereon. In this case, mounting may also take placereleasably, such as, for example, with the aid of screws. The mountingdirection corresponds to the two arrows in FIG. 2 which run parallel toone another.

In the valve housing 2 are provided a first port 4 for exhaust gasinlet, indicated in FIG. 1 by an arrow, and, on the side opposite theexhaust gas inlet, two further ports, to be precise a second port 5indicated at the top in FIG. 2 by an arrow, for the bypass, and a thirdport 6 indicated at the bottom in FIG. 2 by a second arrow and leadingto the cooler (not illustrated).

The regulation element 3 arranged in the valve housing 2 has a valvestem 7 which is connected to an actuation device 8 for regulating theposition of the regulation element 3 in the valve housing 2, illustratedat the top in FIG. 2, the actuation being indicated by a double arrow.The valve stem 7 in this case projects through a cover 9 which sealinglycloses the valve housing 2 and which is screwed to the valve housing 2by means of four screws (not illustrated). In this case, a seal (notillustrated), preferably a flat seal, is preferably provided between thevalve housing 2 and the cover 9. According to the present exemplaryembodiment, actuation takes place by means of a pressure-regulatedvacuum cell. According to a variant illustrated in FIG. 10, actuationtakes place with the aid of an electric motor, the output of which isconnected to the valve stem 7 via a gear.

The regulation element 3, which has a conical surface area 10 with avertex angle of 45°, which is arranged coaxially to the longitudinalaxis of the valve stem 7, has, on the top side 11 and underside 12closing off the conical surface area 10, in each case a profile bentaccording to the flow conduction requirements (cf. FIG. 3A to FIG. 3C),the edges 13 forming the control edges which, depending on the positionof the regulation element 3, completely or partially release or closethe ports 4, 5 and 6 in the valve housing 2. The regulation principle isillustrated in FIG. 4B in which one of the two control edges can be seenthrough the port. In the event of a counterclockwise rotation of thevalve stem 7, the port is gradually closed, and, in the event ofclockwise rotation, the port is released further until the control edgecomes in front of the port again from the other side and graduallycloses this.

In order sealingly to close the corresponding port or ports in theclosed state, in the valve housing 2 a valve seat 14 is provided whichis provided with a conical surface area 15 which is designedcorrespondingly to the conical surface area 11 and through which thefirst port 4 penetrates. The vertex angle is in the present caselikewise 450. The second port 5 is spatially connected to the regionabove the conical surface area 15 and the third port 6 is spatiallyconnected to the region below the conical surface area 15.

By virtue of this configuration of the rotary piston valve 1, theregulation element 3 can perform the function of a shutoff valve and atthe same time the function of a distributor flap, so that only oneregulation element 3 is required. An illustration of the free crosssection for the gas flow via the rotary angle of the regulation element3 is illustrated in FIG. 5, in the upper region of FIG. 5 the rotarypiston valve 1 being illustrated in section in various positions to makethe configuration of the rotary piston clear, the illustrated positionbeing identified in the diagram by an arrow at the corresponding point.

Illustrated on the left is the completely closed position, shortlybefore the opening of the cold air duct (that is to say, the lower thirdport 6), which in the present case is assigned to a rotary angle ofapproximately 0°. In this case, the inlet of the exhaust gas through thefirst port 4 is prevented due to the position of the rotary piston whichcompletely closes the first port 4.

As is evident from the illustration, at a rotary angle of 0° toapproximately 130° there is “cold” quantity regulation, that is to saythe exhaust gas passes, here in an approximately linear relation betweenthe free cross section and the rotary angle, through the first port 4into the rotary piston valve 1 and through the third port 6 to theexhaust gas cooler. In this rotary angle range of the rotary piston, thesecond port 5 is completely closed on account of the profile of theupper edge 13′ which in the region of the first port 4 is in bearingcontact against the conical surface area 15 of the valve seat 14 abovethe first port 4, so that the exhaust gas is conducted solely throughthe lower third port 6 to the cooler. In this case, at a rotary angle ofthe rotary piston of approximately 110°, the free cross section is atits absolute maximum, that is to say, in this position of the rotarypiston, the largest exhaust gas quantity can flow through the rotarypiston valve 1, the entire exhaust gas stream in the present case beingconducted solely to the exhaust gas cooler.

At a rotary angle of approximately 130° to 230°, temperature regulationtakes place, that is to say the gas is conducted both through the secondand through the third port 5 and 6, the lower third port 6 being closedslowly with an increase in rotary angle, and the upper second port 5being opened slowly, and, at a rotary angle from approximately 230° to360°, the third port 6 being completely closed. In order to make thispossible, the two edges 13′ and 13″ are arranged so as to run in theregion of the first port 4, so that it is possible for the exhaust gasto flow past upward and downward. The profile of the edges 13 is in thiscase designed in such a way that the free cross section remains constantover the entire angle range, so that the exhaust gas quantity flowingthrough the rotary piston valve 1 is also essentially constant.

At a rotary angle of above 230° to approximately 330°, “hot” quantityregulation takes place, that is to say the exhaust gas is conductedsolely through the second port 5. In this rotary angle range of therotary piston, the third port 6 is completely closed on account of theprofile of the lower edge 13′ which in this rotary angle range comes tobear below the first port 4, so that the exhaust gas is conducted solelythrough the second port 5 and therefore through the bypass, past theexhaust gas cooler to the bypass. The free cross section decreasesessentially linearly as a function of the rotary angle over the angularrange of “hot” quantity regulation.

As illustrated in FIG. 7, the valve stem 7 has a margin 16 offlange-like design and, at its end region 17 projecting through thecover 9, a toothing 18. A sleeve 19 and a disk 20 are pushed onto thevalve stem 7 for guidance and sealing off. Above the disk 20 arearranged two cup springs 21 which bear against the inside of the cover 9and compensate play in the valve stem longitudinal direction. The cupsprings 21 consist, for example, of Inconnel or Waspalloy.

According to a preferred lower-friction variant which is illustrated inFIG. 8 and in which elements identical to or having the same action asthe exemplary embodiment described above are provided below withreference symbols higher by 100, a sleeve 119 corresponding to thesleeve 19 has on its end face 130 bearing against a disk 120 a groove131 running with beveled side walls in the radial direction. The disk120 has itself a region 132 which projects in the direction of thesleeve 119 and which corresponds in its form to that of the groove 131.

For positioning the sleeve 119 in the valve housing 102, in a laterallyprojecting marginal region 133 a further groove 134 is provided, intowhich a projection 135 formed on the cover 109 projects, so that thesleeve 119 is seated securely in terms of rotation on the valve stem107. Moreover, the sleeve 119 is firmly connected to the cover 109 in away not illustrated in any more detail. The disk 120 is connectedsecurely in terms of rotation to the valve stem 107 in a way notillustrated in any more detail.

In order to reduce the friction during a rotation of the valve stem 107,the valve stem 107 and therefore also the regulation element areslightly displaceable in the axial direction, in the present case by theamount of 0.1 mm, the surface areas of the regulation element and valveseat bearing against one another only in the closed state. The axialdisplaceability is made possible by the interaction of the projectingregion 132 of the disk 120 fixed with respect to the valve stem and ofthe groove 131 in the sleeve 119 fixed with respect to the valve housingand by the resilient prestress of the cup springs 121 arranged above thedisk 120 correspondingly to the first exemplary embodiment. The cupsprings 121 prestress the disk 120 and therefore the valve stem 107downward, so that the projecting region 132 is always in bearing contactwith the upper end face 130 of the groove 131 of the sleeve 119. Whenthe projecting region 132 is in bearing contact with the upper end face130, the valve stem 107 and therefore also the regulation element aredisplaced upward by the amount of the height of the projecting region132 by means of the sleeve 119 fixed with respect to the valve housing.When the projecting region 132 enters the groove 131, the valve stem 107and therefore also the regulation element descend until the two surfaceareas are in complete bearing contact and the rotary piston valve 101 iscompletely closed.

FIGS. 11 to 13 illustrate various exemplary embodiments of ahigh-pressure exhaust gas return system in simplified form. Identicalparts are given the same reference symbols. The power of an internalcombustion engine depends on the cubic capacity, the rotational speedand the mean gas pressure. By a supercharging of the engine, the fillingcan be improved considerably and therefore the engine power increased.The fuel/air mixture or the air is precompressed completely or partiallyoutside the cylinder. In an engine with an exhaust gas turbo charger,the exhaust gases drive the turbine, and the latter drives thecompressor. The compressor assumes intake and delivers a precompressedfresh gas charge to the engine. A charge air cooler in the charge linedischarges the compression heat into the surrounding air. The cylinderfilling is thereby further improved.

Exhaust gas return serves for cooling the exhaust gas as far aspossible. The returned exhaust gas no longer participates in combustionin the internal combustion engine, but heats up. Overall, due to thereturned exhaust gas, the temperature in the internal combustion engineor the engine is lowered. Owing to low temperatures in the engine, thegeneration of nitrogen oxides, which is highly dependent on thetemperature in the engine, can be reduced.

The fuel/air mixture is sucked in by a compressor 1102 via an air filter1101 and supplied to an engine 1104. The exhaust gas passes from theengine 1104 to a turbine 1106 which drives the compressor 1102. Betweenthe engine 1104 and the turbine 1106, which is also designated as aturbo charger turbine, an extraction point 1108 is provided which isconnected to a return point 1109. The exhaust gas is supplied to theengine 1104 again via the return point 1109. Between the extractionpoint 1108 and the return point 1109 is arranged a valve according tothe invention, in particular as described with reference to FIGS. 1 to10, and which is designated below as a heat exchanger valve 1111 or elseas a combination valve. The combination valve 1111 is connected to anexhaust gas cooler 1112 which comprises a bypass. This bypass isproduced in one piece with the cooler housing. In a further version, notillustrated, of the invention, the bypass is designed as a separatepipeline which, in particular, bypasses the cooler. A charge air cooler1114 is inserted between the compressor 1102 and the return point 1109.

The high-pressure exhaust gas return systems illustrated in FIGS. 12 and13 resemble the exhaust gas return system illustrated in FIG. 11.Identical reference symbols are used to designate the same parts. Inorder to avoid repetition, reference is made to the above description ofFIG. 11. Only the differences between the individual exemplaryembodiments are dealt with below.

In the high-pressure exhaust gas return system illustrated in FIG. 12, aheat exchanger valve 1121 according to the invention, which is alsodesignated as a combination valve, is inserted between the extractionpoint 1108 and the return point 1109. The combination valve 1121 isconnected to a U-flow cooler. Depending on the switching position of thecombination valve 1121, either the returned exhaust gas passes,uncooled, directly through the combination valve 1121 from theextraction point 1108 to the return point 1109 or the returned exhaustgas is conducted by means of the combination valve into the U-flowcooler, is cooled in the U-flow cooler 1122 and only then arrives at thereturn point 1109.

In the high-pressure exhaust gas return system illustrated in FIG. 13,between the extraction point 1108 and the return point 1109 is arrangeda combination valve 1131 with a two-stage cooling device which comprisesa high-temperature exhaust gas cooler 1132 and a low-temperature exhaustgas cooler 1133.

FIGS. 14 to 16 illustrate various exemplary embodiments of alow-pressure exhaust gas return system in simplified form. The fuel/airmixture is sucked in by a compressor 1102 via an air filter 1101 andsupplied to an engine 1104. The exhaust gas from the engine 1104 isexpanded in a turbine 1106 which drives the compressor 1102. Downstreamof the turbine 1106 is arranged an extraction point 1108 which isconnected to a return point 1109. The return point 1109 is arrangedupstream of the compressor 1102. A charge air cooler 1114 is insertedbetween the compressor 1102 and the engine 1104. A diesel particlefilter 1140 with an oxidation catalyst is inserted between the turbine1106 and the extraction point 1108. A heat exchanger valve 1141, whichis also designated as a combination valve, is inserted between theextraction point 1108 and the return point 1109. The combination valve1141 is connected to an exhaust gas cooler 1142 which is equipped with abypass. A condensate separator 1144 is inserted between the exhaust gascooler 1142 and the return point 1109. An exhaust gas backpressure valve1145 is arranged after the extraction point 1108 in the flow direction.A charge air throttle 1147 is inserted between the return point 1109 andthe air filter 1101.

FIGS. 15 and 16 illustrate similar low-pressure exhaust gas returnsystems to that in FIG. 14. The same reference symbols are used todesignate identical parts. In order to avoid repetition, reference ismade to the above description of FIG. 14. Only the differences betweenthe individual exemplary embodiments are dealt with below.

In the exemplary embodiment illustrated in FIG. 15, a heat exchangervalve 1151, which is also designated as a combination valve, is insertedbetween the extraction point 1108 and the return point 1109. Thecombination valve 1151 is connected to a U-flow cooler 1152. Dependingon the switching position of the combination valve 1151, either thereturned exhaust gas passes, uncooled, directly through the combinationvalve 1151 from the extraction point 1108 to the return point 1109 orthe returned exhaust gas is conducted into the U-flow cooler 1152 bymeans of the combination valve, is cooled in the U-flow cooler 1152 andonly then arrives at the return point 1109.

In the exemplary embodiment illustrated in FIG. 16, between theextraction point 1108 and the return point 1109 is arranged acombination valve 1161 with a two-stage cooling device which comprises ahigh-temperature exhaust gas cooler 1162 and a low-temperature exhaustgas cooler 1163.

1. A valve, especially a rotary piston valve, for regulating thetemperature and quantity of the returned exhaust gas in internalcombustion engines, with a valve housing and with a regulation elementwhich is arranged in the latter and which cooperates with a valve seatformed in the valve housing, for regulating the throughflow of a fluid,and which is mounted rotatably in the valve housing, wherein theregulation element has a conical surface area.
 2. The valve as claimedin claim 1, wherein the regulation element has a top side and anunderside and the surface area arranged between them, which areseparated from one another by edges, the regulation element, as afunction of its angular position in the valve housing, conducting thefluid past its top side, past its underside or past both its top sideand its underside or completely shutting off the port for the fluid. 3.The valve as claimed in claim 2, wherein the top side and the undersideare formed by curved surfaces.
 4. The valve as claimed in claim 1,wherein the valve seat has a conical surface area which has the samevertex angle as the conical surface area of the regulation element. 5.The valve as claimed in claim 1, wherein the vertex angle of the cone is30° to 90°, in particular 40° to 50°.
 6. The valve as claimed in claim1, wherein the regulation element is mounted displaceably in thelongitudinal direction of the valve housing.
 7. The valve as claimed inclaim 6, wherein the regulation element is displaceable in thelongitudinal direction by at most 0.5 mm, preferably by at most 0.1 mm.8. The valve as claimed in claim 6, wherein the regulation element bearsagainst the valve seat only in the event of a complete closing of thevalve and in the event of opening is arranged so as to be slightlyremoved from the valve seat in the longitudinal direction.
 9. The valveas claimed in claim 1, wherein the valve can be actuated with the aid ofa pressure-regulated vacuum cell or an electric motor.
 10. The valve asclaimed in claim 1, wherein the regulation element is arranged on avalve stem which projects through a sleeve fixed with respect to thevalve housing.
 11. The valve as claimed in claim 10, wherein the sleevefixed with respect to the valve housing has in one end face at least onegroove which runs in the radial direction and which cooperates with aprojecting region which is formed on a disk arranged fixedly in terms ofrotation on the valve stem.
 12. The valve as claimed in claim 11,wherein the groove has a contour corresponding to the projecting region.13. The valve as claimed in claim 1, wherein at least one spring,especially a cup spring, is arranged on the valve stem.
 14. A valve,especially a rotary piston valve, for regulating the temperature andquantity of the returned exhaust gas in internal combustion engines,with a valve housing and with a regulation element which is arranged inthe latter and which cooperates with a valve seat formed in the valvehousing, for regulating the throughflow of a fluid, and which is mountedrotatably in the valve housing, wherein the regulation element arrangedrotatably in the valve seat is designed in such a way that it regulatesthe throughflow quantity of the fluid supplied to the valve through afirst port, in a first angular position range, with the second portclosed, in the form of straightforward throughflow regulation to a thirdport, in a subsequent second angular range, in the form of a regulationof the fluid distribution to the second and the third port and, in thefollowing third angular range, in the form of straightforward regulationof the free cross section of the second port, with the third portcompletely closed.
 15. The valve as claimed in claim 14, wherein therelation between the angular position of the regulation element and thecross section released for the throughflow of the fluid is essentiallylinear in the region of the first angular range and/or of the thirdangular range.
 16. The valve as claimed in claim 14, characterized by anabsolute maximum of the released cross section between the first and thesecond angular range.
 17. The valve as claimed in claim 14, wherein thecross section released overall is essentially constant in the secondangular range.
 18. The valve as claimed in claim 14, characterized by aconical surface area of the regulation element which completely orpartially closes or releases the first port.
 19. An exhaust gas returnsystem with an internal combustion engine, especially an engine, whichis supplied with exhaust gas branched off at an extraction point andreturned via a return point, wherein a heat exchanger valve device witha valve as claimed in claim 1 is inserted between the extraction pointand the return point.
 20. The exhaust gas return system as claimed inclaim 19, wherein the heat exchanger valve device is connected to anexhaust gas cooling device.
 21. The exhaust gas return system as claimedin claim 19, wherein the heat exchanger valve device is integrated intothe exhaust gas cooling device.
 22. The exhaust gas return system asclaimed in claim 19, wherein the heat exchanger valve device isconnected in a materially integral manner to the exhaust gas coolingdevice.
 23. The exhaust gas return system as claimed in claim 19,wherein the exhaust gas cooling device has a bypass.
 24. The exhaust gasreturn system as claimed in claim 19, wherein the exhaust gas coolingdevice comprises a U-flow cooler.
 25. The exhaust gas return system asclaimed in claim 19, wherein the heat exchanger valve device is arrangedupstream of the exhaust gas cooling device, as seen in the flowdirection from the extraction point to the return point.
 26. The exhaustgas return system as claimed in claim 19, wherein the heat exchangervalve device is arranged downstream of the exhaust gas cooling device,as seen in the flow direction from the extraction point to the returnpoint.
 27. The exhaust gas return system as claimed in claim 19, whereinthe heat exchanger valve device comprises a high-temperature exhaust gascooler and a low-temperature exhaust gas cooler.
 28. The exhaust gasreturn system as claimed in claim 19, wherein the heat exchanger valvedevice is arranged upstream or downstream of the high-temperatureexhaust gas cooler or of the low-pressure exhaust gas cooler, as seen inthe flow direction from the extraction point to the return point. 29.The exhaust gas return system as claimed in claim 19, wherein theexhaust gas return system is formed by a high-pressure exhaust gasreturn system.
 30. The exhaust gas return system as claimed in claim 19,wherein the exhaust gas return system is formed by a low-pressureexhaust gas return system.